1. Field of the Invention
This invention relates to a bookbinding apparatus for automatically binding a bundle of sheets.
2. Related Background Art
There is known an on-line apparatus which continuously effects from the image formation on sheets to the work of binding the sheets having images formed thereon, by a series of flows. This on-line apparatus adopts a method of pasting and binding a plurality of sheets (a bundle of sheets) having images formed thereon. In this pasting and bookbinding, use is made of a strip-like bind tape to which a hot melt adhesive agent is applied.
When sheets having images formed thereon which are moving in the on-line apparatus are to be bound, the sheets having images formed thereon which are moving are first stacked on an aligning tray and are aligned thereon. A bind tape cut into a strip-like form is then disposed on the bound edge of the bundle of sheets aligned, and subsequently the bind tape is heated by a heater to thereby melt a hot melt adhesive agent. The melted hot melt adhesive agent flows among the sheets and pastes the bundle of sheets. In this case, right and left side heaters bend the right and left side portions of the bind tape and adhesively secure them to the front and back covers of the bundle of sheets.
The on-line apparatus according to the prior art is provided with one kind of tape-up bind tape having a particular width size, and this take-up bind tape is cut into a predetermined length and supplied to a bookbinding portion. In this case, a bind tape having a width size suitable for the thickness of a bundle of sheets to be bound is chosen by an operator and is set in the on-line apparatus.
However, if as in the above-described example of the prior art, only one kind of bind tape can be supplied, the work of changing the bind tape to be used each time the thickness of a bundle of sheets to be bound changes must be done by the operator. This has led to much labor and time and to the problem that depending on the thickness of a bundle of sheets to be bound, the length of the margin to paste up adhesively secured to the front and back covers of the bundle of sheets becomes irregular and the quality of bookbinding is spoiled.